1. Field of the Invention
The present invention relates to testing of C-type modems of a digital subscriber line access multiplexer by way of a remotely provisioned R-type modem.
2. Description of Related Art
With reference to FIG. 1, a typical prior art architecture for DSL distribution from a service provider's Central Office (CO) 2 to each of one or more customers 4 is illustrated. Each customer 4 includes a so-called R-type DSL modem 6 (hereinafter “R modem 6”) which is linked to a so-called C-type DSL modem 8 (hereinafter “C modem 8”) located in a so-called Digital Subscriber Line Access Multiplexer (DSLAM) 10 disposed communicatively between CO 2 and each customer 4.
Each R modem 6 is connected to a corresponding C modem 8 located in DSLAM 10 via a DSL line 12, e.g., a twisted cable pair, that can be up to 18,000 feet in length. For each R modem 6 there is a corresponding C modem 8 in a DSLAM 10. Each DSLAM 10 is configured to house a plurality of C modems 8. Models of DSLAMs exist that have 10's, 100's or 1000's of C modems 8 that can service a corresponding number of R modems 6. When each C modem 8-R modem 6 pair is communicatively synchronized, a constant flow of DSL signal traffic exists between them in a manner known in the art. Each modem 6 and 8 is an intelligent device capable of decoding messages embedded in DSL signal(s), and responding to the messages or forwarding them further on in the network if warranted.
Each DSLAM 10 is operative for terminating DSL signals received from R modems 6 communicatively coupled to C modems 8 thereof via DSL lines 12, for aggregating any data residing on the received DSL signals onto a high speed Ethernet line 14, and for forwarding the aggregated data to CO 2. More specifically, an Ethernet switch 16 of each DSLAM 10 is operative for aggregating the data extracted from DSL signals received from R modems 6 communicatively coupled to C modems 8 thereof via DSL lines 12, and for combining said data onto the corresponding Ethernet line 14. Each Ethernet line 14 can be any suitable and/or desirable physical type and can use copper or fiber media, or some combination thereof. FIG. 1 shows a so-called Gigabit Ethernet (GigE) as high speed Ethernet line 14. However, this is not to be construed as limiting the invention.
Each Ethernet line 14 communicatively couples the corresponding Ethernet switch 16 of a DSLAM 10 to an Ethernet switch 18 located within CO 2. Ethernet switch 18 aggregates the data received via each Ethernet line 14 onto one higher speed Ethernet line 19. FIG. 1 shows a so-called 10 Gigabit Ethernet (10 GigE) line as the high speed Ethernet line 19. However, this is not to be construed as limiting the invention.
The architecture shown in FIG. 1 can be scaled by coupling any suitable and/or desirable number of DSLAMs 10 to CO 2 in the manner described above. For example, tens or hundreds of DSLAMs 10 could be communicatively coupled to CO 2 in the manner described above.
In order to facilitate testing of each C modem 8 thereof, each DSLAM 10 includes a switch matrix 20 which is responsive to commands received from Ethernet switch 16, which commands are received by Ethernet switch 16 via the corresponding Ethernet line 14. More specifically, each switch matrix 20 includes a plurality of switches configured and operative for enabling the DSL port of each C modem 8 to be connected, one-at-a-time, to a DSL test port 22 of DSLAM 10.
To facilitate testing of each C modem 8 of a particular DSLAM 10, an R modem 6′, like the R modems 6 of each customer 4, is installed between the DSL test port 22 of the DSLAM 10 and an Ethernet test port 24 of DSLAM 10, the latter of which is coupled to Ethernet switch 16 of DSLAM 10.
With reference to FIG. 2 and with continuing reference to FIG. 1, each R modem 6′ includes a line interface 26, an analog front end (AFE) 28, a digital signal processor (DSP) 30 and a microprocessor 32.
Line interface 26 of R 6′ modem transformer couples R modem 6′ to a DSL line 34 coupled between switch matrix 20 and the DSL port of R modem 6′, splits the DSL signal into its upstream and downstream components, and amplifies the DSL signal. Line interface 26 then passes conditioned downstream signals to AFE 28. Upon receiving downstream signals from line interface 26, AFE 28 does some additional amplification and filtering, and digitizes said signals with 10-14 bit resolution at 18 Msamples/sec. The digitized signals are then sent to DSP 30. Upstream signals input into AFE 28 by DSP 30 as 10-12 bit digitized signals at 9 Msamples/sec are converted into analog DSL signals by AFE 28. These analog DSL signals are then sent to line interface 26 for amplification and coupling to DSL line 34.
DSP 30 decodes digitized signals received from AFE 28 into ATM cells or Ethernet packets and encodes ATM cells or Ethernet packets received from microprocessor 32 into discreet multi-tone (DMT) signals in accordance with ANSI Standard T1.413. The digitized signals passed between AFE 28 and DSP 30 are digitized DMT signals which are either being transmitted upstream or downstream.
ATM cells received by microprocessor 32 from DSP 30 must be packetized for transport over an Ethernet line 36 that runs between the Ethernet port of R modem 6′ and Ethernet test port 24 of DSLAM 10. Microprocessor 32 does this function, removing data from the ATM cells, creating Ethernet packets with this data, and sending these Ethernet packets over Ethernet line 36. If microprocessor 32 receives Ethernet packets from DSP 30, it is not necessary that microprocessor 32 modify these Ethernet packets for transmission over Ethernet line 36. Accordingly, microprocessor 32 simply dispatches these Ethernet packets over Ethernet line 36.
While the foregoing description of the various functional blocks of R modem 6′ focused primarily on the transmission of data downstream, it is believed that it would be apparent to one of ordinary skill in the art that the block diagram elements of R modem 6′ can also be utilized to transmit data upstream. Accordingly, a detailed description of the transmission of data upstream will not be included herein.
In use of each R modem 6′, a test system controller 38 coupled to Ethernet line 19, e.g., either directly or via an IP network 40, signals a desired switch matrix 20 via the corresponding Ethernet switch 16 to connect one C modem 8 of DSLAM 10 to DSL test port 22 thereof. At a suitable time thereafter, test system controller 38 causes the corresponding R modem 6′ to establish DSL connectivity with the C modem 8 coupled to DSL test port 22 by switch matrix 20. Desirably, this DSL connectivity is an automated function between R modem 6′ and the C modem 8 under test that requires no further intervention of test system controller 38.
Assuming DSL connectivity is established, at a suitable time, test system controller 38 can retrieve data regarding the DSL connectivity, such as, without limitation, maximum connectivity rate. Also or alternatively, test system controller 38 can cause Ethernet packets to be supplied to R modem 6′ via Ethernet switch 16. R modem 6′ converts these Ethernet packets into analog DSL signals which it transmits to the C modem 8 coupled to DSL test port 22. This C modem 8 converts the analog DSL signals into Ethernet packets which it transmits to test system controller 38 or any other desired system (not shown) coupled to IP network 40. Thus, as can be seen, not only can the DSL connectivity of each C modem 8 of DSLAM 10 be tested, but also the ability of each C modem 8 to convert analog DSL signals into Ethernet packets which can be transmitted to a specific address on IP network 40 for analysis, evaluation and/or to determine whether said C modem 8 is functioning properly.
While the use of an R modem 6′ for testing C modems 8 of a DSLAM 10 as shown in FIG. 1 is technically effective, it is not cost effective. Accordingly, it is desirable to provide a lower cost solution to the R modem 6′ associated with each DSLAM 10 for testing the C modems 8 thereof while providing the same level of functionality.